On the road - inconsistent voltage, help diagnosing please!

Discussion in 'Crazy-Awesome almost Dakar racers (950/990cc)' started by jconly, Aug 8, 2012.

  1. Gustavo.Ramos

    Gustavo.Ramos Long timer

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    My 990Adv suddendly started acting similar...

    At rest 12,7v,
    Engine started 13,4v
    At revs >2,5k 12,9 - 13,1v

    Hard to start, a few weeks ago, a freeway stretch at >100mph, stoped at fuel station, battery dead. After jump starting with cables from a car, returned home and when arrived at garage hit the start again and fired fairly well. A few other rides and it seems the faster i go, the less charge it get...which is consistent with voltages above. This may be good to avoid speeding tickets but adds alot of stress about having the big-twin not cranking properly when necessary..

    battery is brand new. I'm either leaning to bad VR or faulty battery.

    Coincidence it start acting like this when battery was replaced :huh
    #41
  2. AdvGa

    AdvGa Long timer

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    #42
  3. Gustavo.Ramos

    Gustavo.Ramos Long timer

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    Did a few try this try that.

    Using 3 different batteries, 2 YTZ14S and one YT9... whatever from my 690, all crank the engine, fire up and idle correctly. All return the same results, 13 to 13,3 idling, and less that 13 while reving the engine. All 3 batteries faulty!? possible but not likely..

    Verified the stator charge output, all 3 combinations return >60 VAC @ 5k rpm.

    Guess the stator is doing its job.

    Verified regulator connections, a bit dirty but nothing serious, and the result was the same. I'm more and more inclined to a faulty regulator... Tomorrow i'm borrowing one.
    #43
  4. Gustavo.Ramos

    Gustavo.Ramos Long timer

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    To the OP i'm not trying hijacking the thread, although it sure looks like!

    So today i got a few more piece on my puzzled head. A friend borrowed me his '06 990S voltage regulator so i could test on my bike.

    Usually these test are followed by a big grin, cause we're almost sure what is the cause. Well...not this time! The voltage was slightly different

    engine off: 12,8v
    engine idling: 13,9v
    pushing the revs: 13v ~ 13,2v

    WTF!? :huh

    Put the regulator back on friends bike, started the engine, same results. WTFFFF????

    Just to complicate a bit more, there was a brand new Dakar at the shop, tested the voltage and it showed:

    engine off: 12,9v
    idling 13,9v
    at revs 14v

    Shouldn't it be at 14,5 or something?
    #44
  5. AdvGa

    AdvGa Long timer

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    #45
  6. jconly

    jconly Been here awhile

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    Not a problem!!
    By all means, lets make this a place to sort these issues.

    In response to the 13.5-15V healthy number.. I would agree that this is a good range of values one should see. Anything over or under is dangerous. But I disagree that this is an acceptable "working range," if you will.

    Since installing my Mosfet I've seen some interesting things.
    When I first installed it, I was seeing that 14-14.4 number that I was looking for.
    As time has progressed, that peak output has dropped a little, and the scale has slid down slightly.
    I get the best numbers on the open road, in the city here, and certainly idling, performance drops.

    So what's the deal... heat.

    I feel like these regulators are in a terrible place on our bike. Hidden by the skidplate, with no windflow to keep them cool. Call me crazy, but IMO it shortens their life span. They slowly die.


    My suggestions... Order up a Shindengen.
    Find a good place to mount it with solid airflow.

    I'm about to take my back on the TET all the way down to Miami, and I'll be keeping a close eye as I go and while down there. If theres any place that will put a hurting on it, its being in a city much further south. If the regulator beings to slide further down that scale, I'll be looking for a new place to mount it.
    #46
  7. bomose

    bomose Long timer

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    I'm just getting back to this thread.I had a few times on my trip that my bike was hard to start, mostly when cold.Batteries Plus twice checked the battery and said it was 100%. They were wrong. It was the battery. After I replaced it, no problems at all.
    #47
  8. Gustavo.Ramos

    Gustavo.Ramos Long timer

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    So my 990 was having a bit of a hard time or strange mood regarding battery charge. After disassembling the electric area near the battery and cleaning everything i found this:

    [​IMG]

    What i find strange is that such important part is so poorly crafted to avoid moisture contamination.

    New starter relay on order
    #48
  9. jconly

    jconly Been here awhile

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    Agreed, it's really not a good place for those components.
    Same can be said for the VR... why does it live in such a hot place? Right under the engine, shielded from cooling by the bash plate. Should be up and out front, why not mount were they put the oil coolers on the race bikes?
    #49
  10. Gustavo.Ramos

    Gustavo.Ramos Long timer

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    Some decisions are purely void of meaning. Being in the auto industry (cars) i've seen some things that would made me scratch severely my already bald head...

    Back to my bike, after changing the starter relay all the fussing with improper charging is gone. Onto the next issue!
    #50